public class OpenFile {
public static void OpenFile() throws IOException {
    ArrayList<String> lineList = new ArrayList<String>();
    Variablen.desktop = Desktop.getDesktop();
    Variablen.fileChooseropen = new FileChooser();
    Variablen.fileChooseropen.setTitle("Open File");
    Variablen.fileChooseropen.setSelectedExtensionFilter(new FileChooser.ExtensionFilter("TXT Files (*.txt)","*.txt"));
    Variablen.fileChooseropen.setInitialFileName("file.txt");
    Variablen.file = Variablen.fileChooseropen.showOpenDialog(null);
    if(Variablen.file != null) {
        Variablen.inputStream = new FileInputStream(Variablen.file);
        Variablen.bufferedReader = new BufferedReader(new InputStreamReader(Variablen.inputStream));
        Variablen.stringBuilder = new StringBuilder();
        String line;
        while ((line = Variablen.bufferedReader.readLine()) != null) {
            lineList.add(line);
        }
    }
        /**
         *  Creating an Array,to save the content and give it to the Textarea
         */
            String[] linearray = new String[lineList.size()];
            lineList.toArray(linearray);
            System.out.println(Arrays.toString(linearray));
            Variablen.bufferedReader.close();
            Variablen.textarea.setText(String.valueOf(linearray));
    }
}
Caused by: java.lang.NullPointerException at sample.OpenFile.OpenFile(OpenFile.java:45) at sample.Controller.ListenOpenFile(Controller.java:14) ... 54 more
